Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include"bits/stdc++.h"
using namespace std;
int dy[4]={0,1,0,-1},dx[4]={1,0,-1,0};
int H,W,ans=0;
char maze[52][52];
int dist[52][52];
queue<pair<int,int>> que;
int main()
{
  cin >> H >> W;
  for(int i=0;i<H;i++){
    for(int j=0;j<W;j++){
      cin >> maze[i][j];
      dist[i][j] = -1;
      if(maze[i][j]=='.')
        ans++;
    }
  }
  dist[0][0] = 0;
  que.push(make_pair(0,0));
  while(!que.empty()){
    int cy=que.front().first,cx=que.front().second;
    que.pop();
    if(cy==H-1&&cx==W-1){
      ans -= dist[cy][cx]+1;
      cout << ans << "\n";
      return 0;
    }
    for(int i=0;i<4;i++){
      int ny=cy+dy[i],nx=cx+dx[i];
      if(ny<0||H<=ny||nx<0||W<=nx||maze[ny][nx]=='#')
        continue;
      if(dist[ny][nx]==-1){
        dist[ny][nx]=dist[cy][cx]+1;
        que.push(make_pair(ny,nx));
      }
    }
  }
  cout << "-1\n";
}